The invention relates to a quick coupling for coupling a tool to the boom of a hydraulic excavator and the like having a quick coupling part at the boom side and a quick coupling part at the tool side, which can be latched to one another via a pair of spaced latching axles, and a power circuit coupling, in particular a hydraulic coupling, for coupling a power connection at the tool side to a power connection at the boom side, wherein the power circuit coupling has a power coupling part at the boom side and a power coupling part at the tool side, which are arranged at the quick coupling part at the boom side or at the quick coupling part at the tool side such that they automatically couple with one another as soon as the two quick coupling parts are pivoted together about a first of the two latching axles into their latching position.
Quick couplings of the pivot type are widespread in hydraulic excavators since they allow a simple and fast changing of different tools such as hydraulic grabs, ditch cleaning shovels, grab tongs and the like. Initially, only one of the two latching axles need to be positioned and brought into engagement for coupling. This can advantageously be a transverse bolt which is hung into a hook-like eyelet on the opposite coupling part. Then the coupling part at the boom side can be pivoted relative to the tool about the latching axle already brought into engagement to hereby find the latching position in which the second latching axle can be latched. The latter is as a rule formed by a pair of latching bolts which can move apart and into corresponding latching bores at the opposite quick coupling part.
Such a fast coupling of the pivot type is known from WO 91/01414 in which an automatic hydraulic coupling is provided which automatically couples a power circuit at the boom side to a power circuit at the tool side when the two quick coupling parts are pivoted together. There are two power coupling parts provided of which one is secured to the quick coupling part at the boom side and the other to the quick coupling part at the tool side, and indeed such that the two power coupling parts are moved towards one another and brought into engagement when the two quick coupling parts are pivoted together about the already latched latching axle. One of the two power coupling parts is movably mounted at the corresponding quick coupling part to compensate the circular movement of the quick coupling parts during the pivoting together.
This known quick coupling is, however, not sufficient in a number of aspects. The power coupling parts do not couple cleanly when the quick coupling parts are moved together so that oil leaking and thus a contamination of the soil can occur. Due to tilting of the power coupling parts, these are subject to great wear and can even be damaged.
It is therefore the underlying object of the present invention to provide an improved quick coupling of the kind first mentioned which avoids the disadvantages of the prior art and advantageously further develops the latter. In particular, an improved arrangement of the power coupling should be provided which allows a leak-free and defect-free coupling of the power circuits at the boom side and at the tool side.
In accordance with the invention, this object is solved by a quick coupling as described herein. Preferred embodiments of the invention are also described herein.
In accordance with the invention, the power coupling parts are moved towards one another in an exactly linear manner. A linear guide is provided for the power coupling parts which forces the power coupling parts into a relative movement with respect to one another along a straight line against the circular pivot movement. To allow the compensation of the pivot movement, at least one of the two power coupling parts is mounted at the corresponding quick coupling part movably relative thereto. It is, however, provided in a further development of the prior art that the movably mounted power coupling part compensates the pivot movement during the moving together of the quick coupling parts and moves precisely such that an exact linear movement takes place between the two power coupling parts.
In a further development of the invention, the linear guide has at least one guide element at the boom side and at least one guide element at the tool side which enter into engagement with one another on the closing of the power circuit coupling before the two power circuit coupling parts, in particular their connection connectors, enter into engagement with one another. The linear guide therefore enters into and out of engagement on the pivot movement of the two quick coupling parts about the already latched first latching axle such as the power coupling parts. The engagement of the guide elements of the linear guide takes place, however, before the engagement of the connection connectors of the power coupling parts such that the linear guide of the power coupling parts is ensured from the start. No tilting can take place and a precise linear movement is ensured over the whole coupling path of the power coupling parts. The guide elements of the linear guide are therefore in particular components formed separately from the actual power coupling elements, i.e. the connector members. They are, however, preferably fixedly arranged at the power coupling parts or can be moulded to these.
The linear guide can generally be made in different manners. Optionally, a cam track can be provided for the movably mounted power coupling part or for the movably mounted power coupling parts. A cam-like control of the movement of the movable power coupling part(s) can also be provided. In a further development of the invention, however, there are preferably provided as guide elements at least one guide bolt at one of the power coupling parts and at least one guide bore at the other power coupling part. The guide bolt is pushed into an exact fit into the complementary guide bore when the power coupling parts are moved together, whereby a linear movement is ensured. Preferably, a pair of guide bolts spaced from one another and associated guide bores are provided, with the connection connectors being able to be arranged between the guide bolts or guide bores respectively. The guide bolts extend with their longitudinal axes parallel to the direction in which the connector connections can be pushed onto one another. As connection connectors, the power coupling parts can have female and male connector members known per se which can be pushed into one another.
The guide bolt(s) of the linear guide preferably have a special shape which prevents a tilting during insertion into the complementary guide bore. In particular, each of the guide bolts can have a rounded head, a cylindrical guide section and a constriction which is provided between the head and the cylindrical guide section. In the region of the constriction, the guide bolt has a diameter reduced with respect to the head or with respect to the guide section. The rounded head can also be inserted into the guide bore with a slight angular offset. An alignment or a compensation of the angular offset takes place when the cylindrical guide surface axially spaced from the bolt head likewise comes into engagement with the guide bore.
At least one of the two power coupling parts is movably mounted relative to the associated quick coupling part. Preferably only one is movably mounted while the other is rigidly secured to the other quick coupling part. In this way, a simple arrangement is achieved which nevertheless allows the required compensation of the pivot movement.
The movability of the mounting of the corresponding power coupling part is preferably formed in a multi-axial manner. In particular the mounting of the power coupling part can allow at least one tilting movement about an axis parallel to the first latching axle and a movement in a direction perpendicular to the first latching axle. It preferably also permits a pushing movement parallel to the first latching axle and/or a tilting movement about a tilting axis perpendicular to the first latching axle. With such a comprehensive movable mounting, lateral offset, for example as a result of imprecisions in the assembly, can also be compensated. In addition, the arrangement of the power coupling parts can also be produced more favourably due to coarser tolerances.
In a further development of the invention, one of the two power coupling parts is mounted on a spring device, in particular on a pair of compression springs. The compression springs can be rigidly secured to the corresponding quick coupling part and jointly bear the corresponding power coupling part. The compensation of the pivot movement with respect to the corresponding quick coupling part takes place by deformation of the spring device.
To achieve a secure moving together of the power coupling parts, a limitation of the spring path in the direction of the coupling movement can be provided. In a further development of the invention, a pressure ram can be provided on which the movable power coupling part sits in tiltable and/or displaceable manner.
The pressure ram preferably has a rounded head which can engage approximately centrally between the spring elements of the spring device at the power coupling part. The pressure ram presses the two power coupling parts reliably and securely onto one another in the final stadium of the coupling movement. The pressure ram can advantageously be of changeable length. The pressure ram can in particular be made resiliently to avoid damage and to allow a compensation of tolerances, with the spring constant of the pressure ram being able to be substantially harder than that of the resilient mounting of the power coupling part. In a further development of the invention, the pressure ram can be made as a hydraulic ram, i.e. it can be moved out or biased into its moved out position by a pressure medium. In this way, greater pressure can be applied to the movably mounted power coupling part, preferably towards the end of the coupling movement or after the fully moving together of the power coupling parts, so that the power coupling parts can be reliably held in their moved together position.
The hydraulic pressure with which the pressure ram holds the two power coupling parts together is adapted to the respective operating conditions in a particularly advantageous manner. The force holding together the power coupling parts is always selected to be so high that the parts are completely held together without play at any time. On the other hand, movement is not constantly with a maximum force which would be sufficient to hold the parts together under all operating conditions. The latter is disadvantageous with a solution by means of a spring. If the pressure ram should hold the power coupling parts together solely by spring force, the spring must be dimensioned so large that it holds the power coupling parts together under all conditions so that forces would act over wide paths which would be much too large. The pressure force can advantageously be varied with a hydraulic ram.
The pressure ram can in particular be fed with a pressure medium from one of the pressure medium circuits to be fed, i.e. the pressure ram is subjected to the action of the pressure fluid which is forwarded to the tool coupled via the power coupling. In this way, the holding together force also increases in dependence on the respective operating pressure of the tool. In an advantageous further development of the invention, the areal ratio between the effective working cylinder area of the pressure ram which is acted on by the pressure medium and the effective connector area, i.e. the effective flow cross-section through the coupling which is exposed to pressure medium perpendicular to the coupling direction in the region of the connectors, is selected to be larger than 1. An advantageous design can consist of the areal ratio amounting to approximately 5/4. The holding together force applied by the pressure ram is always higher due to this areal ratio than the maximum occurring force which attempts to press the power coupling apart. If the operating pressure in the pressure medium lines to be coupled increases, the force acting on the pressure ram and thus the holding together force also increases. Usually a plurality of pressure medium connectors are provided. Likewise, a plurality of pressure rams can be provided. In this case, the ratio of the sum of the effective working cylinder areas and the sum of the connector areas is selected in the previously described manner. In a further development of the invention, the cylinder of the pressure ram or the cylinders of the pressure rams can be put into flow connection with a plurality, in particular all, of the pressure medium lines of the pressure medium circuit to be coupled. A valve arrangement is preferably interposed between the pressure medium lines and the cylinder(s) which ensures that always that one of the pressure medium lines which has the highest pressure is in connection with the pressure ram. It is achieved in this way that the pressure ram is always acted on with the sufficiently large pressure. As the valve arrangement, the pressure medium lines can be switched together in pairs via shuttle valves so that, so to say, always the higher pressure is asserted.
The pressure ram can be fed from different sections of the pressure medium circuit. It is possible to connect the pressure medium circuit at the boom side to the pressure ram. The fluid connectors are usually provided with leak securing means so that the pressure ram can also already be actuated when the connectors are not yet connected, with the connectors being connected by the moving out of the ram. In a preferred aspect of the invention, however, the cylinder(s) are fed from the pressure medium circuit at the tool side, i.e. they are only acted on by pressure when the power circuit coupling, and in particular its fluid connectors, are moved together and the connectors have coupled.
In a further development of the invention, it can also be provided to move the power circuit coupling parts together with a time delay with respect to the pivoting together movement of the quick coupling. This can be simply achieved in that the hydraulic acting on the pressure ram is effected with a time lag.
A separate hydraulic circuit can be provided to actuate the pressure ram.
The movably mounted power coupling part and thus the pressure ram can generally be arranged at the boom side. In a further development of the invention, however, they are provided at the tool side.
It must be ensured between the pressure ram and the power coupling part acted upon by it that relative movements can take place, and indeed both tilt movements and displacement movements perpendicular to the longitudinal axis of the pressure ram. On the one hand, the movably mounted power coupling half compensates the pivot movement of the quick coupling halves to the extent that a linear movement is made out of the circular movement. Furthermore, relative movements occur as a consequence of play and the like. To permit this offset, the pressure ram and the power coupling half acted upon by it are movable relative to one another. To nevertheless enable large forces to be transmitted, it can be provided that the pressure ram is provided at the end face with a pressure cap which has a planar end surface such that it can sit tightly and areally on the essentially planar power coupling part. To permit tilting movements, it is preferably provided that the pressure cap and the pressure ram have areas arched in complement to one another with which they sit on top of one another such that the pressure cap can tilt on the ram itself and nevertheless an areal connection is provided.
To securely hold together the two power coupling parts even in rough operation, a form-locking latching of the two power coupling parts can be provided alternatively or additionally to the hydraulic pressure ram. In a further development of the invention, it can be provided that the guide bolt of the linear guide is locked when this is moved into the complementary guide bore. In particular a movable transverse bolt can be provided which is mounted in the power coupling part which has the said guide bore. The latching transverse bolt can preferably be acted on hydraulically. The transverse bolt can advantageously interact with the constriction of the guide bolt, i.e. when the guide bolt is fully moved into the guide bore, the latching transverse bolt is moved in tangentially to the guide bore such that it projects into the guide bore, and indeed in the region in which the constriction of the guide bolt is located.
In a further advantageous embodiment of the invention, a separate bar can be provided for the form-locking latching of the two power coupling parts in their coupled position. A bar flap is preferably provided. A setting cylinder which is preferably hydraulically operable can be provided for actuating the bar. The bar can be acted on by a spring such that it is biased in its latching position. In this way, the actuating means only needs to be actuated for unlatching.
In a further development of the invention, a pre-centring means is provided in addition to the linear guide for the two power coupling parts on the pivoting together of the quick coupling parts. The pre-centring means aligns the two power coupling parts towards one another by so much before the engaging of the linear guide that the corresponding guide elements of the linear guide can engage into one another in accordance with their purpose. This in particular has advantages if, in non-attentive operation, the first latching axle is not accurately adjusted or fully moved in on the pivoting together of the two quick coupling parts. In this case, alignment errors of the power coupling parts can occur which could effect damage to the power circuit coupling on the moving together. The pre-centration likewise corrects excessive alignment errors of the power coupling parts relative to the corresponding quick coupling part which can occur, for example, due to the movable mounting of at least one of the power coupling parts.
The pre-centring means can be made in different manners. It preferably has a pair of centring surfaces which slide off one another on the pivoting together of the quick coupling parts and of which one is provided at the movably mounted power coupling part. The other of the interacting centring surfaces can be provided at the other power coupling part. In a farther development of the invention, it can be arranged at the opposite quick coupling part. They are in particular arranged such that they enter into engagement in front of the linear guide.
In a further development of the invention, in addition to the pre-centring means, a pivot guide can be provided which ensures that the two quick coupling parts can only be pivoted together in their desired alignment to one another, i.e. when the first latching axle is properly aligned. The pivot guide prevents damage to the hydraulic coupling by moving together the quick coupling parts with an offset. In the latter case, the connection members, or the guide bolts, of the power coupling parts would likewise move towards one another with an offset and cause damage. The pivot guide has guide surfaces preferably provided at the solid pivot coupling parts themselves, which guide surfaces slide past one another or also slide off on one another on a proper alignment of the quick coupling parts on pivoting together about the first latching axle. They can be made in centring manner such that on pivoting together, the two quick coupling parts press into their desired alignment to one another in which the first latching axle is properly aligned. The guide surfaces advantageously prevent an offset of the two quick coupling halves with respect to one another before the second latching axle is latched, in particular when the power coupling parts have already come into engagement with one another. Such an offset would necessarily have the consequence of damage to the power coupling. The guide surfaces can in particular be made such that they interact with the first latching axle, which is formed in hook-like fashion, as soon as they are pushed over one another, so that an offset or a slipping of the quick coupling halves with respect to one another is prevented.
In accordance with a particularly advantageous embodiment of the invention, the power circuit coupling is a mounting unit which can be subsequently mounted to the two quick coupling parts. It is not an integral component of the quick changer. The power circuit coupling is preferably made such that even already existing quick changers can be retrofitted.
To ensure good accessibility to the power circuit coupling, in a further development of the invention, the power circuit coupling can be arranged outside the latching axles of the two quick coupling parts. The power circuit coupling in this case does not lie with difficult accessibility between the two latching axles, but can, for example, be easily reached for cleaning. In addition, in this connection, it is not disposed in the intermediate space between the two latching axles which is prone to the collection of contamination and dirt.
In a further development of the invention, the power circuit coupling is arranged within abutting areas of the quick coupling part at the tool side and/or of the quick coupling part at the boom side, in particular such that in the state of the two coupling parts separated from one another, the power circuit coupling parts do not abut the ground when the corresponding quick coupling part is placed on the ground. The two quick coupling parts can preferably each have two spaced carrier members substantially perpendicular to the latching axles and the power coupling parts can each be arranged transversely thereto between two carrier members which belong together. They are disposed in the protected region between the perpendicular carrier members of the quick coupling parts. The carrier members of the quick coupling parts are pushed into one another or over one another in the region of the latching axles. Unlike the prior art, the quick coupling part on the boom side can be free of a base plate which extends parallel to the latching axles and on which the power coupling part would be arranged. It is hereby avoided that when the coupling part at the boom side is placed on the ground with its base plate, the power coupling part arranged thereon is not pressed into the ground.
In a further development of the invention, the two power coupling parts are each made in essentially plate-like form. The already mentioned male or female connector members, which form the power connectors, are arranged on the plate-like carrier of the power coupling parts. The guide bolts or guide bores can be rigidly secured or worked in at a spacing therefrom.